This invention relates to therapeutic tables, or beds, and more particularly, to a kinetic therapeutic table which reciprocally rotates a patient support from one side to the other and which is otherwise adjustable.
Kinetic therapeutic tables which slowly, reciprocally rotate a patient support to cause different parts of the patient's anatomy to support his weight are well known. Such kinetic therapeutic tables are intended for use by patients who are incapable of substantial voluntary movements. The voluntary movements needed to eliminate the formation of bedsores, lung congestion, venal thrombosis and other maladies which develop from immobility are substituted by periodic movements of the therapeutic table. Examples of such therapeutic tables are shown in U.S. Pat. Nos. 2,076,675 of Sharp; 2,950,715 of Brobeck; 3,434,165 of Keane; 3,748,666 of Seng; 4,107,490 of Keane; 4,175,550 of Leininger et al. and 4,277,857 of Svehaug.
Since the patient support is tilted, it is necessary to provide lateral support to secure the patient against falling off the bed. The lateral supports must fit snugly to the patient's body and must therefore be adjustable for proper fit with various patients of different size. In the bed of Keane 3,434,165, elongate, upstanding side members provide lateral support. These are mounted by means of depending shafts which fit into tubular receivers, or mountings, which in turn are fastened to the underlying patient support. While the tubular receivers are laterally adjustable, the location of the inner side of the lateral support which presses against the patient is not adjustable relative to the tubular mountings.
In addition to lateral support, it is also sometimes necessary to provide means for restraining the patient's knee against movement above the patient support and means to support the patient's foot. In U.S. Pat. No. 3,434,165 of Keane, for instance, such a knee restraint and foot support are mounted to the ends of separate L-shaped members which are mounted to, and extend upwardly from, a central portion of the frame to which the patient support is mounted. This inconveniently also places the adjustment mechanisms for the knee restraint and the foot support in the central portion of the table where it is relatively more difficult to reach by attendants, particularly if they are of short stature. In addition, this central protrusion requires the patient support to be centrally divided.
It is also known to provide the patient support in the form of multiple panels which can be individually moved away from beneath the patient to gain access for treatment, bathing or the like. In Keane U.S. Pat. No. 3,434,165 these panels are hinged to a central portion of the frame. Thus, although the panels are movable for access, they are not easily removable entirely from the frame. Such non-removability is desirable for cleaning of the panel and for better access and for situations in which the panel is not needed for supporting the patient, as in the case of an amputee. In addition, complete removability permits easy substitution of special purpose panels which may be required.
For purposes of improving access to the patient, it is also desirable to stop the movement of the bed at any selected nonhorizontal position. However, it is also necessary to quickly move the bed to a horizontal position in the event of an emergency. It is also important to be able to switch off power to the motor which provides the rotary drive to the motor at any angular position of the bed in the event of shorting or other malfunction of the motor. In Keane U.S. Pat. No. 4,107,490, a power off switch is provided in a kinetic therapeutic table, but it is mechanically prevented from being activated to terminate power to the rotary drive motor except when the bed is in one of certain preselected positions. Once locked in one of these positions, the bed can only be moved to a horizontal position by disengaging the patient support from the drive by means unassociated with the position locking means.
A further problem with known kinetic therapeutic beds which move the patient about a pivot axis aligned with the elongate axis of the table is that the patient support is located beneath the pivot axis. Accordingly, instead of the patient support rotating, it unpleasantly swings or sways. It is known to provide a pivot axis aligned with the patient support in a therapeutic table which tilts or rocks about an axis transverse to the elongate direction of the patient support, as shown in U.S. Pat. No. 4,277,857. However, the problem is not alleviated, since the patient's head and feet are still caused to swing because of their substantial distance from the pivot axis. In known therapeutic tables which rotate about an axis aligned with the elongate direction of the pivot axis, such as shown in Keane U.S. Pat. No. 3,434,165 and Leininger et al. U.S. Pat. No. 4,175,550, the pivot axis is undesirably located above the patient support.
A movable drive support is needed to mount the patient support for rotary movement relative to the frame which provides a smooth and steady movement with minimum noise. In the aforementioned beds, the patient supports are simply mounted to narrow pivot axles at opposite ends. This disadvantageously places all the weight of the patient and patient support on the narrow axles. If the narrow pivot axles are driven directly, they provide little mechanical advantage. If the bed is driven by an eccentric cam spaced from the axle, then non-uniform drive movement is developed. In U.S. Pat. No. 3,302,218 Stryker, a rotatable bed is shown supported by an annular member, but no drive is associated with the annular member, and it is disadvantageously located intermediate the ends of the patient support.
In addition to rotary movement about an elongate axis, it is also desirable to be able to pivot or tilt the bed about an axis extending substantially transverse to the rotary axis. When the patient is tilted to a position with his head at a level beneath the level of his feet, the patient is said to be in a Trendelenburg position, and when he is in a position with his feet lower than his head, he is in a reverse Trendelenburg position. Devices which provide for this type of movement for a patient support are known as illustrated by U.S. Pat. Nos. 2,076,675 of Sharp; 3,434,165 of Keane; 3,525,308 of Koopmans et al. and 4,277,857 of Svehaug. In U.S. Pat. Nos. to Sharp 2,076,675 and Keane 3,325,308 the beds also rotate. In the device of Svehaug U.S. Pat. No. 4,277,857, a diagonal track provided at opposite ends of the bed is employed to alternately raise and lower the two ends. However, a single drive is provided for continuous rocking movement of the patient support, and independent control of movement of the two ends of the bed is not obtainable. Generally, while known devices perform somewhat satisfactorily, they employ structure which have a high profile or are unduly heavy or mechanically complex.
It is also desirable to adjust the degree of maximum tilt imparted to the patient support. In known therapeutic tables such adjustment is limited to a few selected discrete angles of tilt and such adjustment is accomplished by mechanical means.